Basso?™s Diamante SV Disc Frameset was designed alongside its rim brake brother. That they knew this was coming meant that Basso thought about how to design for both rim and disc brakes before committing to their shapes and lay-ups. As a result, this Disc version not only shares a geometry, but the frame shapes as well.
As with the rim brake version, they employ a mix of Torayca carbon-fiber plies, including their high modulus T1000 and T800 cloth. The lay-up has been altered, with plies moved around to different places, and a few added to better deal with the stresses of disc braking. But the overall result is largely the same. A great riding, light, aero road bike.
Weight. Aero shaping typically adds some weight to improve aerodynamics and retain stiffness frame stiffness. They need more material to get the elongated shapes, and since the elongated shapes are often in opposition to the needs of propelling a bicycle, even more material needs to be added. At 890g for an unpainted 53 frame, and 400g for the fork, they only added a little weigh from their rim version and are still pretty light for an aero bike regardless of braking method. Then again, their more traditional Diamante is only 790g for the frame. And the two frames share the same torsional stiffness values at the bottom bracket and head tube. This is due to both the frame shaping as well as the wide BB86 bottom bracket shell and 1 1/8??to 1 ½??tapered steerer tube.
The aero shaping is both dramatic and subtle. When seen from the side, the bike almost looks traditional. But the head tube and fork legs are shaped to smoothly move the wind around them, the fork crown smoothly blends into the downtube, the downtube is a modified Kamm Tail design with is lowered and almost U-shaped to better shroud bottles and fight torsional flex, and the seat tube is shaped to shroud the rear wheel. The shortened seat stays are aero shaped and also mean that the Kamm Tail seat tube has less turbulence behind it, and the less support adds vertical compliance at the top of the seat tube.
At every point of the bike, you?™ll find things that improve on what you?™ve come to expect as standard. The proprietary seat post, 350mm long with 15mm of setback and with measurement markings on the back, is U-shaped and goes into the frame through an elastomer. The gasket damps road vibrations and sits above the integrated three-bolt fixing system they?™ve designed. These bolts sit flush with the back of the seat tube. The shaping is such you can fit 28mm tires without issue, impressive for such short chainstays, opening up road choices, and long-distance comfort.
The frame comes with a Basso stem and a customizable head tube complete with spacers. The stem angle is -11 degrees and the lengths come as follows: size 45 frame comes with a 100mm stem, the 48 a 100, 51 a 110, 53 a 110, 56 a 110, 58 a 120, 61 a 120. Reading the geometry chart, you?™ll notice that the head tube is relatively short. That?™s assuming you are running your stem slammed or nearly slammed. The frame comes with Basso?™s Kit Comfort System, which includes three 5mm spacers and a the Kit Comfort head tube extender, which raises the effective head tube length by 20mm, as it provides you with a taller cup into which you install the upper headset bearing. And with this installed, you can then add the 15mm of spacers. The result is a single frame that has 35mm of flexibility in terms of where your stem sits. You can run the stem slammed to get the head tube length in the spec sheet, and then add spacers up to 15mm. If you want the head tube to be 20mm higher than the spec sheet, add the Kit Comfort. Then you can put spacers on top of that. This way, the frame works for those who prefer the super-low position of a pro or a more upright position favored by the less-flexible.